The invention relates to a improved windlass assembly for water craft.
A form of windlass having a gypsy (in which a line and/or chain executes only a single turn between inward and outward runs)is commonly used in marine craft to haul and veer the anchor rode i.e. the line and/or chain to which the anchor is attached. When the anchor is dropped, it is desirable that the anchor rode can pay out freely under the weight of the anchor. A free fall mode allows the gypsy to rotate freely. However, to haul in the anchor, the drive mechanism of the windlass must engage the gypsy, which can then rotate to wind in the anchor rode.
There are several problems with this type of windlass. Often after the anchor rode has been paid out and the anchor dropped, the windlass is inadvertently left in the free fall mode. This is a particular problem if the craft stays at anchor for a period of time, because the mode of the windlass is frequently forgotten. Because the drive mechanism is not engaged, subsequent operation of the windlass will not haul the anchor rode.
If the windlass has been insufficiently tightened or has worked loose during a passage, it is possible for the anchor to fall overboard under its own weight and drag out the anchor rode after itself. This can be particularly dangerous if the boat is travelling at high speed.
The present invention provides a windlass which overcomes these problems by providing a means for controlling the xe2x80x98free fallxe2x80x99 of the anchor rode and a locking system which prevents inadvertent free fall and invariably allows the anchor rode to be hauled at will.
One aspect of the present invention is a windlass having a rotatable central drive shaft adapted to rotate a gypsy,
a locking lever,
the locking lever being mounted so as be movable between a first position in which the gypsy is coupled to the drive shaft
and a second position in which the gypsy can rotate relative to the shaft
the locking lever being at all times resiliently biased to adopt the first position,
the windlass additionally comprising a controlling means adapted to modulate the amount of friction to which rotation of the gypsy relative to the shaft is subject.
In this specification, the meanings of xe2x80x98upperxe2x80x99 and xe2x80x98lowerxe2x80x99 correspond to the orientations in the figures which are designated as views from above or below.
The drive shaft may be linked to a manual or motorised drive of any convenient type.
The gypsy comprises a pair of jaws about which the anchor rode passes. Each jaw may be manufactured independently and the two jaws fixed together subsequently. Preferably the jaw portions are identical, for ease of manufacture. The gypsy has a central bore through which the drive shaft passes. The gypsy is rotatably mounted on the drive shaft.
The drive shaft may be shaped to limit the movement of the gypsy down the shaft, for example by means of a shoulder beyond which the gypsy cannot pass. Preferably, a lower member is positioned between gypsy and the shoulder. The lower member is preferably a tight press fit on shoulder of the drive shaft so that drive can be transmitted from the drive shaft to the lower member. The lower member contacts the gypsy and maintains the position of the gypsy on the drive shaft. Friction may be induced by this contact which opposes the rotation of the gypsy relative to the drive shaft and the lower member.
The lower member is preferably cone-shaped. The conical surface of this cone-shaped lower member may then be received into a correspondingly tapering recess in the lower surface of the gypsy.
The upper surface of the gypsy preferably comprises a gypsy lock which may be secured to the upper surface of the gypsy by any convenient means, for example welding, or, alternatively, it may be an integral part of the gypsy. The gypsy lock is adapted so that it can be engaged by the locking lever. To this end, it may comprise one or more pockets which can receive a lower tooth of the locking lever. More preferably, two, three or four pockets may be employed. When the tooth is engaged in a pocket of the gypsy lock, rotation of the locking lever can drive the rotation of gypsy.
The locking lever may be pivotally mounted by any convenient means. It is shaped so that it can engage the gypsy lock. It is preferable that a tooth is located on a lower surface of the locking lever which can be received in a pocket on the upper surface of the gypsy lock. The pocket may be engaged by pivoting the locking lever and lowering the tooth.
The locking lever is urged towards a position in which the lower tooth can engage the pocket of the gypsy. This may be achieved by any convenient means but preferably a spring is used to urge the locking lever into the engaging position.
The controlling means which modulates the amount of friction to which rotation relative to the drive shaft may be subject, may comprise a friction zone positioned on the lower surface of the locking lever on the opposite side of the fulcrum from the tooth. This friction zone may comprise a rough surface. The friction zone may be shaped so as to comprise a protrusion which can be received by a correspondingly shaped groove in upper surface of the upper half of the gypsy. When the locking lever is pivoted so that it cannot engage the gypsy, the friction zone is consequently lowered so that it contacts the upper half of the gypsy and frictionally impedes rotation of the gypsy relative to the locking lever and the drive shaft. The extent of impedance is determined by the amount of pressure put on the locking lever. In this way, rotation of the gypsy may be controlled.
In preferred embodiments, the drive shaft transmits drive directly to the top cap. This may be achieved, for example, by the engagement of a splined region of the drive shaft with an internally splined bore of the top cap. It is preferable, in these embodiments, that the top cap transmits drive directly to the locking lever. This may be achieved for example by the engagement of the top cap with side walls of the locking lever. Gypsy rotation relative to the drive shaft may be controlled in these embodiments by the use of a friction zone on the locking lever.
It is preferable that the top cap allows the locking lever to be manipulated so that the assembly can be switched between the drive and free fall modes. The top cap may comprise an aperture in the top cap through which an elongate implement may act on the locking lever, for example by pushing down on it, so as to disengage it from the gypsy lock. The elongate implement may be part of a switch mechanism or may form part of a tool such as a handle or a plunger. When the implement ceases to act on the locking lever, the resilient action of spring will urge the locking lever back into a position where it can engage the gypsy lock, thereby preventing rotation of the gypsy relative to the drive shaft.
The aperture and the implement may be shaped so as to prevent the rotation of the implement within the aperture, for example, both may be splined. This allows the implement to be used as a handle to tighten and loosen the top cap in those embodiments in which rotation of the top cap controls the amount of friction on the rotation of the gypsy during xe2x80x98free-fallxe2x80x99.
In embodiments in which a friction zone is situated on the locking lever, the elongate implement may be used to apply pressure on the locking lever and thereby control rotation of the gypsy relative to the drive shaft.
An upper member may contact the upper half of the gypsy. In a less preferred embodiment, this upper member is driven by the drive shaft. In these embodiments, drive is transmitted to the upper member by the engagement of a region of the drive shaft with a bore of the upper member. This engagement may be facilitated by splines on one or more of the engaging surfaces.
In embodiments in which drive is transmitted to an upper member, the upper member is shaped so that it can engage the locking lever and drive it. In these embodiments, the upper member may have one or more pockets which can receive the lower tooth of the locking lever and preferably the upper member has two, three or four pockets. When the tooth is engaged in a pocket of the upper member, rotation of the upper member drives the rotation of locking lever. When the tooth is also engaged in a pocket of the gypsy lock, drive can be transmitted from the upper member, through the locking lever to the gypsy.
Friction induced by the contact between the upper member and the gypsy impedes rotation of the gypsy relative to the upper member. The amount of friction induced may be controlled by increasing the pressure exerted by the upper member on the gypsy.
The upper member may be cone-shaped, in which case the conical surface of this cone-shaped upper member is preferably received in a correspondingly tapered recess in the upper surface of the gypsy.
In embodiments in which an upper member is driven by the drive shaft, it is preferable that the tooth may also be received into a pocket in the upper member, so that the tooth can simultaneously engage both the upper member and the gypsy.
In this case, the controlling means may comprise a top cap engaged on a externally threaded terminal region of the drive shaft. Rotation of the top cap will adjust its position along the drive shaft, and, because the drive shaft is shaped to limit the downward movement of the windlass components, this will alter the pressure on the upper and lower members. The greater the pressure on the members, the greater the frictional engagement between the members and the gypsy and the more difficult it is for the gypsy to rotate relative to the drive shaft.
During operation, the anchor rode is paid out, when the anchor is dropped, by switching the windlass assembly to a free-fall mode, in which the gypsy-can rotate on the drive shaft. This switching is carried out by pivoting the locking lever so that it disengages the gypsy lock. The rotation of the gypsy and hence the free fall of the anchor can then be controlled by altering the frictional resistance using the controlling means.
When the anchor rode is hauled in, the locking lever is urged by the spring into engagement with the gypsy. In embodiments in which the locking lever is driven directly by the top cap, the locking lever will itself rotate with the drive shaft, engage the gypsy lock within one revolution or less and then transmit drive to the gypsy. Alternatively, in embodiments which an upper member is driven, this will rotate with the drive shaft and engage the locking lever within one revolution. The upper member will then drive the locking lever so that it engages the gypsy lock within one further revolution. Drive can then be transmitted to the gypsy.